Anaerobic adhesives

ABSTRACT

Polymerizable acrylic monomers, and anaerobic adhesives which contain such monomers, wherein the acrylic monomers contain internal chain unsaturation in addition to terminal acrylic unsaturation.

This is a division of application Ser. No. 576,149, filed Feb. 2, 1984,now U.S. Pat. No. 4,530,988, which is a division of application Ser. No.265,539, filed May 20, 1981, now U.S. Pat. No. 4,431,787, issued Feb.14, 1984, which is a continuation-in-part of application Ser. No.100,244, filed Dec. 4, 1979 abandoned, which is a division ofapplication Ser. No. 647,217, filed Jan. 7, 1976, now U.S. Pat. No.4,209,604.

This invention relates to polymerizable acrylic mononers and toadhesives containing such monomers. More particularly, this inventionrelates to acrylic monomers and adhesives containing same whichanaerobically polymerize, that is, cure in the absence of air.

The inhibiting effect of oxygen to the cure of acrylic monomers has beenknown for many years. This apparently adverse condition was transformedinto something potentially valuable by the invention in U.S. Pat. No.2,628,178 wherein a highly reactive monomer was prepared by bubbling airthrough a heated and agitated polyether glycol dimethacrylate ester, soas to form peroxides in the monomer chain. The oxygenated ester monomerremained liquid as long as aeration continued, but polymerized to asolid when aeration was discontinued. Unfortunately, this system hadlittle commercial value due to the inherent problems of keeping themonomer fluid by aeration. Thereafter, in U.S. Pat. No. 2,895,950, achemical solution to the problem of keeping the dimethacrylate monomerfrom solidifying without aeration was set forth. It was disclosed that,by adding a hydroperoxide, the dimethacrylate ester could be cured(polymerized) at room temperature by placing the mixture between steelplates. On the other hand, when stored in a glass or plastic container,sufficient oxygen from the air in the head space diffused into theacrylic liquid, and kept it from polymerizing.

Since certain metal ions act as catalysts in decomposing thehydroperoxides, enabling commercially feasible cure times, most of themarket for anaerobic adhesives has developed in bonding metal to metal.For example, anaerobic adhesives are used as (1) thread lockingcompounds which prevent loosening caused by vibration, (2) sealingcompounds for threaded, flanged and sleeved joints to retain fluids andprevent leaking, (3) retaining compounds to bond parts havingcylindrical symmetry such as gears or pulleys onto shafts, and (4)bonding compounds which serve as structural adhesives.

Generally, depending upon the ultimate use of the anaerobic adhesive,these adhesives should have high shear strength, good hot strength, andfast cure speed. Unfortunately, prior art anaerobic monomers, andmixtures thereof, tend to exhibit some of these importantcharacteristics, but not all simultaneously. For example, prior artmonoacrylate monomers, such as hydroxyethyl methacrylate, cure quiterapidly yielding an adhesive exhibiting excellent shear strength, butrelatively poor hot strength. Furthermore, prior art polyacrylatemonomers, containing two or more acrylate groups, such as ethyleneglycol dimethacrylate or trimethylolpropane trimethacrylate, exhibitgood hot strength, but relatively poor shear strength. Also, severalrecent Japanese patents disclose anaerobically curing acrylic monomersprepared by the reaction of phthalic anhydride with mono or diacrylates.See Japanese patent Nos. 73/89,947, 73/9460 and 71/31,680. Thesemonomers, however, do not simultaneously exhibit excellent shearstrength and hot strength.

In view of the foregoing, there is a continuing need in the anaerobicadhesive art for improved monomers and adhesive systems. Accordingly, itis a principal object of the present invention to provide improvedpolymerizable monomers for use in anaerobic adhesive systems.

It is also an object of the present invention to provide improvedacrylic monomers which, when cured, simultaneously exhibit high shearstrength and good hot strength.

It is an additional object of the present invention to provide improvedanaerobic adhesives which exhibit good cure speed, high shear strength,and good hot strength.

It is another object of the present invention to provide novelmonoacrylate and polyacrylate monomers containing internal chainunsaturation in addition to terminal acrylic unsaturation.

As used in the present description and discussion of this invention,"acrylic" shall refer to the group ##STR1## wherein R" is a memberselected from the group consisting of hydrogen, chlorine, methyl andethyl radicals. "Monoacrylate monomer" shall refer to a monomer having aterminal acrylic group, and "polyacrylate monomer" to a monomer havingtwo or more acrylic groups. For ease of discussion, "acrylic monomers"shall be used to refer to both monoacrylate and polyacrylate monomers.

The objectives of this invention are carried out by providingpolymerizable monoacrylates and polyacrylates which contain one or moreolefinically unsaturated polycarboxylic acid residues. The unsaturatedcarbon-carbon double bonds introduced by the polycarboxylic acid groupsenable cross-linking of the monomers during curing, so as to provide acured polymer having exceptional hot strength, as well as excellentshear strength.

The improved monoacrylate monomers of this invention comprise thereaction product of (a) a monoacrylate monomer having a reactive sitecapable of reacting with a carboxyl group and (b) an unsaturatedpolycarboxylic acid or unsaturated polycarboxylic acid anhydride. Thereactive site of the monoacrylate reactant is selected from the groupconsisting of hydroxyl (--OH), primary amine (--NH₂) and secondary amine(--NR'H) groups wherein R' is a benzyl radical or an alkyl group of from1 to 4 carbon atoms, e.g., methyl, ethyl, propyl, butyl radicals.Although the reactive site is most often a terminal reactive site, theinvention includes those monoacrylate reactants having an internalreactive site. Typical monoacrylate monomer reactants which may be usedinclude hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropylacrylate, hydroxypropyl methacrylate, aminoethyl methacrylate,aminopropyl methacrylate, aminoethyl acrylate, aminopropyl acrylate,N-methyl aminoethyl methacrylate and N-benzyl methyl methacrylate. Also,acrylate reactants having a suitable reactive site as defined above canbe prepared by reacting acrylic acid or methacrylic acid withepichlorohydrin, glycidol, styrene oxide, phenyl glycidyl ether, butylglycidyl ether, allyl glycidyl ether, or glycidyl methacrylate.

The other reactant is an unsaturated polycarboxylic acid or anunsaturated polycarboxylic acid anhydride. Typical unsaturateddicarboxylic acids include maleic, fumaric, itaconic and its isomers,allylmalonic and its isomers, allylsuccinic and its isomers, xeronicacids and cetylmalonic acids. Because reaction with the acid anhydrideproceeds much easier than reaction with the carboxylic acid, and becauseno byproducts are formed, it is generally preferred to use theunsaturated acid anhydride. Therefore, this invention will be discussedin terms of reaction with the unsaturated acid anhydride. Although allunsaturated polycarboxylic acid anhydrides are envisioned within thescope of this invention, the unsaturated dicarboxylic acid anhydrides,in particular, comprise the most important reactants. Typicalunsaturated acid anhydrides which may be utilized in the presentreaction include maleic anhydride, itaconic anhydride,tetrahydrophthalic anhydride, as well as the Diels-Alder reactionproduct of maleic anhydride and cyclopentadiene, and the Diels-Alderreaction product of maleic anhydride and methyl-substitutedcyclopentadiene. It should be noted that the Diels-Alder anhydridesmentioned here are bicyclic, containing 2 carboxylic rings, one having 6carbon atoms and the other 5 carbon atoms.

Reaction of the monoacrylate monomer, having the above-defined reactivesite, with the unsaturated polycarboxylic acid anhydride, results incleavage of the anhydride linkage, and formation of a compound having aterminal acrylic group, a terminal carboxylic acid group, and aninternal olefinic carbon-carbon double bond contributed by theunsaturated polycarboxylic acid residue.

The reaction between the anhydride and the acrylate is carried out at atemperature of from about 23° C. up to about 90° C. The reaction may becarried out with or without the presence of a tertiary amine catalystsuch as triethylamine. Generally, the reaction mixture should beagitated and/or aerated in order to promote the reaction. Although themole ratio of reactants is not critical, and may be carried out instoichiometric amounts or with an excess of either, it has beendiscovered that the reaction is preferably carried out when one mole ofthe acid anhydride is used for about every 1.0 to 1.2 moles acrylatereactant. Generally, the reaction proceeds to completion within a periodof from about 1 to 4 hours when reacted in the presence of a catalystand when heated above room temperature.

This new monoacrylate monomer remains liquid in the presence of air oroxygen, but is polymerizable via catalysis to a solid in the absence ofair. It has been discovered that this new monomer, when incorporated inan anaerobic adhesive system, results in a cured polymer whichsimultaneously exhibits good shear strength and hot strength. Thus, thisnew monomer lends itself to improved anaerobic adhesive systems asherein later described.

The reaction and novel monomer may be expressed as follows: ##STR2##wherein R" is as previously defined; R is ##STR3## where R₁ is a memberselected from the group consisting of hydrogen, methyl, ethyl,chloromethyl, methylol, phenyl, methoxyphenyl, methoxybutyl andmethoxyallyl radicals or ##STR4## p is an integer of from 0 to 2, q isan integer of from 1 to 3; R₂ is an unsaturated divalent alkyl orsubstituted alkyl group of from 2-4 carbon atoms or an unsaturateddivalent carbocyclic aliphatic ring of from 4 to 9 carbon atoms, andpreferably 5 or 6 carbon atoms; and X is a member selected from thegroup consisting of --O--, --NH--, or --NR'-- where R' is as previouslydefined.

This novel monoacrylate monomer can undergo chain extending reactionsthrough the terminal carboxyl group by reaction with epoxides orglycidyl ethers or polyols to form ester linkages. Typical chainextending reactants include ethylene oxide, ethylene glycol, propyleneoxide propylene glycol and phenyl glycidyl ether. For example, when thenovel monoacrylate monomer (I) is represented as ##STR5## with A, ofcourse, being ##STR6## then a chain extending reaction between thismonomer and an epoxide or glycidyl ether may be represented as follows:##STR7## wherein R₁ is as previously defined.

The reactive hydroxyl group formed during the esterification of thecarboxyl group with the epoxide or polyol can then undergoesterification with another carboxyl group, supplied by additionalcarboxyl terminated monoacrylate monomer (I) or by another organiccarboxylic acid or anhydride. Thus, suitable carboxylic acid anhydridesinclude phthalic anhydride and its isomers, pyromellitic dianhydride andbenzophenone tetracarboxylic acid dianhydride, as well as theunsaturated dicarboxylic acid anhydrides previously described. Althoughmonomer (I) can first be reacted with a polyol or epoxide as describedabove, and then reacted with additional carboxylic acid or acidanhydride, it is preferable to react the monomer (I), the polyol orepoxide, and the carboxylic acid or anhydride simultaneously. Thereaction product is a novel acrylic monomer defined by the followingstructure: ##STR8## wherein A and R are as previously defined; t is aninteger of from 0 to 20; and R₃ is a divalent radical selected from thegroup consisting of R₂ as previously defined, phenyl, butyl,di-carboxylic acid substituted phenyl and ##STR9## where Ph is phenyl.

One example of such a reaction is the reaction between monomer (I),ethylene glycol and phthalic anhydride; ##STR10##

A particularly valuable reaction of monoacrylate monomer (I), similar tothe chain extending reactions previously described, is the reaction withpolyepoxides, especially diepoxides, to form novel polyacrylate anddiacrylate monomers having two or more internal carbon-carbon doublebonds available for subsequent cross polymerization. This reaction maybe defined as: ##STR11## where R", R and R₂ are as previously defined;R₄ is a member selected from the group consisting of alkyl of 1-4 carbonatoms, alkoxy (oxy alkyl) of 2-120 carbon atoms, alkylidene oxy aryl(oxy alkylidene aryl), methylol alkoxy aryl, cyclohexadiene dioxide,cyclopentadiene dioxide, alkoxy hydantoin and alkoxy aryl sulfone; n is0 or 1; and u is an integer of from 1 to 5.

Suitable polyepoxides that can be reacted with monomer I include thenovolac resins (phenol-formaldehyde epoxides) as described in U.S. Pat.No. 3,301,743. Typical diepoxides that may be utilized include limonenedioxide, 1,4 cyclohexadiene dioxide, 3,4-epoxy-6-methyl cyclohexylmethyl 3,4-epoxy 6-methyl cyclohexane carboxylate, cyclopentadienediepoxide, dicyclopentadiene diepoxide and hydantoin-based diepoxides.However, the preferred diepoxides are the bisphenol diepoxidesrepresented by R₅ --O--Ph--C (R₆)₂ --Ph--O--R₅ where R₅ is an alkylepoxide of from 2-5 carbon atoms, Ph is phenyl and R₆ is hydrogen,methyl, ethyl, propyl or butyl. Thus, monoacrylate monomer (I) can bereacted with 2,2-bis 4-(2',3' epoxy pro-di-poxy)phenyl propane (thediglycidyl ether of bisphenol-A) as follows: ##STR12## where A is aspreviously defined.

The reaction of monomer (I) with polyepoxides or diepoxides to obtainthe novel class of diacrylate monomers (IV) and (V) is generally carriedout under agitation and/or aeration at from about room temperature up toabout 100° C. for greater than about 4 hours. A tertiary amine catalyst,such as triethylamine, may be employed if desired. Although notcritical, approximately stoichiometric amounts of the reactants aregenerally used. It should also be understood that novel monomers (IV)and (V) can be prepared by simultaneous reaction of the anhydride, themonoacrylate having a reactive site, and the polyepoxide or diepoxide.The diacrylate monomers (IV) and (V) remain liquid in the presence ofair but will polymerize in an anaerobic adhesive system in the absenceof air to yield a polymer having exceptional shear strength and hotstrength.

In addition to the above-described chain extending reaction of acrylicmonomer (I) with epoxides, polyols or glycidyl ethers to yieldadditional acrylic monomers such as monomers (II)-(V), acrylic monomer(I) may also be reacted through its terminal carboxyl group with metaloxides or hydroxides, with ammonia, with amines or imines, withalcohols, and with guanidine carbonate. Thus, the oxides or hydroxidesof metals such zinc, calcium, magnesium, sodium and potassium can bereacted with monoacrylate monomer (I) to yield the corresponding metalsalt (alkoxide). Also, ammonia will react with the monoacrylate to yieldthe ammonia salt. Additionally, aliphatic primary or secondary aminesand imines can be reacted with the monoacrylate monomer to yield aminesalts, which salts can be converted to amides by heating. Alcohols reactwith the monomer to yield corresponding esters. Guanidine carbonate willreact with the monomer to yield the guanidine salt thereof. Thus, themonomer may be represented as: ##STR13## wherein R, R₂ and R" are aspreviously defined and Y is H, a monovalent metal, a divalent metal, anamine, ammonia, guanidine, or a short length carbon chain of not morethan about 12 carbon atoms, preferably not more than 6 carbon atoms.

Like prior art acrylic monomers, the novel acrylic monomers of thisinvention are capable of free-radical initiated addition polymerizationat the unsaturated acrylic double bonds in the absence of air. Thisaddition polymerization, in the absence of air, is catalyzed byfree-radical initiators such as peroxides and hydroperoxides, and inparticular, thermally stable organic hydroperoxides such as tertiarybutyl hydroperoxide and cumene hydroperoxide. Other hydroperoxides whichare less stable but more reactive can also be used. The catalyst isgenerally included in the anaerobic adhesive composition in an amount offrom about 0.01 to 10% by weight of the total adhesive composition, andpreferably from about 0.5 to 5.0% by weight. The catalyst is generallyineffective to polymerize the monomer in the presence of oxygen, butwill initiate addition polymerization when air is excluded.

Also, in accordance with established prior art procedures,polymerization of the present monomers can be accelerated byincorporating promoters in the anaerobic adhesive composition. Thesepromoters are tertiary organic amines, imides, sulfimides or mixturesthereof, such as dimethyl aniline, dimethyl-p-toluidine and benzoicsulfimide. The promoters are incorporated in the adhesive composition inan amount of from about 0.01 to 10% by weight, and preferably from about1 to 10% by weight of the adhesive composition.

As is known in the art, anaerobic adhesives should be stabilized inorder to prevent accidental polymerization induced by the presence ofimpurities that tend to catalyze polymerization of the acrylic monomereven in the presence of air. The addition of inhibitors such asquinones, e.g., benzoquinone, greatly prolongs the shelf-life of theadhesives. These inhibitors need be present in the adhesive compositionin only very small amounts, usually from about 10 to 1000 parts permillion (ppm), and preferably from about 50 to 500 ppm.

Many optional ingredients may be incorporated in the final adhesiveformulation, depending on the properties desired. For example, aplasticizer may be added in amounts of up to 50% by weight of thecomposition as needed. Also, a viscosity control agent, such as fumedsilica, may be added, usually in amounts of less than about 5%. Further,lubricants and dyes may be added, if desired.

It should also be understood that the anaerobic adhesive compositions ofthis invention may include prior art acrylic monomers blended with thenovel acrylic monomers described herein (monomers I-V). Thus, thepresent novel acrylic monomers may be blended with hydroxyethylmethacrylate, hydroxypropyl methacrylate, trimethylolpropanetrimethacrylate, dibromopropyl methacrylate, diethylene glycoldimethacrylate, triethylene glycol dimethacrylate, dimethylaminoethylmethacrylate, tetraethylene glycol dimethacrylate, dipropylene glycoldimethacrylate, methyl methacrylate, ethyl methacrylate, propylmethacrylate, polyethylene glycol dimethacrylate, di(pentamethyleneglycol)dimethacrylate, n-butyl methacrylate, trimethylolpropanetriacrylate, tetraethylene glycol diacrylate, isobutyl methacrylate,tetraethylene glycol diacrylate, isobutyl methacrylate, tetraethyleneglycol di-(chloroacrylate), diglycerol diacrylate, diglyceroltetramethacrylate, butylene glycol dimethacrylate, ethylene glycoldimethacrylate, neopentyl glycol diacrylate, and tetrahyrofurfuralmethacrylate. It will be clear to those in the art that the above isonly a partial list of available polymerizable acrylic monomers, andthat all such known polymerizable acrylic monomers may be beneficiallyblended with the novel acrylic monomers (I-V) to form improved anaerobicadhesive systems.

As has been previously discussed, acrylic monomers (I-V) containinternal chain unsaturation provided by the residue of the unsaturatedpolycarboxylic acid or anhydride. Polymerization of these monomers inthe absence of air (curing) is achieved by addition polymerizationthrough the acrylic unsaturation. However, unlike prior art anaerobicadhesive systems, monomers (I-V) contain non-acrylic internal chainunsaturation and are thus capable of cross-polymerization through theseinternal olefinic unsaturated sites. The resulting cross-polymerizedadhesive exhibits exceptional hot strength, as well as good shearstrength. Additionally, it is believed that only a portion of theanhydride residue unsaturation is cross-polymerized during normalcuring, and that a substantial amount of anhydride residue unsaturationremains for subsequent cross-polymerization during application of heat.This is extremely important where the anaerobic adhesive is to be usedin an application where it will be subjected to heat. In such asituation, additional cross-polymerization occurs, thus furtherimproving the hot strength of the polymer.

In the foregoing description of this invention many references have beenmade to shear strength and hot strength. In the following examplesmention will be made of breakaway strength and prevailing strength.Breakaway strength is the torque required to begin initial movement of abolt relative to a nut which have been sealed by the curing of ananaerobic adhesive. The breakaway strength may be measured at roomtemperature or at various elevated temperatures. For purposes of thisdescription, breakaway strength at room temperature shall be equated toshear strength. Typical prior art anaerobic adhesives exhibit breakstrengths of from about 50 inch-lbs. up to in excess of about 300inch-lbs.

Prevailing strength is the average torque required to rotate a boltrelative to a nut through a rotation of 360° after initial breakaway.This torque may be measured by taking torque measurements at 90°, 180°,270° and 360°, then dividing by 4. Another means of determining thisprevail torque is to measure the torque required for a rotation of 180°.The prevailing strength may be measured at room temperature or atvarious elevated temperatures. For purposes of the present description,hot strength shall be equated to the prevailing torque at a givenelevated temperature. Typical prevailing torques measured at roomtemperature range from about 20 inch-lbs. up to a maximum of about 300inch-lbs. Typical prior art prevailing torques measured after 2 hours at300° F. range up to a maximum of about 130 inch-lbs.

The invention will be described further in connection with the examplesset forth below which are for purposes of illustration only.

EXAMPLE I

An acrylic monomer representative of monomers (I) was prepared byreacting an unsaturated carboxylic acid anhydride with hydroxyethylmethacrylate. Forty-nine grams (0.5 mols) maleic anhydride were combinedwith seventy-eight grams (0.6 mols) hydroxyethyl methacrylate in a4-neck round bottom flask equipped with a condenser, agitator,thermometer and bubbler tube. Agitation was started and 5 mls. oftriethylamine was added. The contents were heated at 80°-90° C. for 4hours with agitation and aeration, then cooled to room temperature.

EXAMPLE II

The shear strength and hot strength of the monoacrylate monomer preparedin Example I was compared with that of a prior art monoacrylate monomerprepared by the reaction of phthalic anhydride with hydroxyethylmethacrylate. Both the maleic-derived monomer and phthalic-derivedmonomer were formulated with identical curing and stabilizing systems toprovide, respectively, anaerobic adhesive systems A and B. The adhesivecompositions were placed between the mating threads of cleaned 3/8 inchdiameter plain steel fasteners (16 threads per inch), and allowed tocure 9 days at room temperature. Torque measurements in inch-lbs. weretaken at room temperature, after holding at 120° F. for 2 hours, andafter holding at 205° C. for 2 hours then cooling to 120° C. Thefollowing results were observed:

    ______________________________________                                                             Prior Art                                                       Adhesive A    Adhesive B                                                      Breakaway                                                                             Prevailing                                                                              Breakaway Prevailing                                        Torque  Torque    Torque    Torque                                     ______________________________________                                        Room Temp                                                                              340       228       344       360 +                                  120° C.                                                                         60         32       15       12                                      120° C. after                                                                   82        200       43      110                                      precondition-                                                                 ing at 205° C.                                                         ______________________________________                                         + means bolt sheared                                                     

The results show that both adhesive systems exhibit good shear strength(Breakaway torque at room temperature), but that the maleic-derivedmonomer system A exhibits a tremendously improved hot strength(prevailing torque at elevated temperatures).

EXAMPLE III

In order to demonstrate that such improved hot strength can be impartedto acrylate monomer blends, 55 parts by weight of the monomer of ExampleI was blended with 45 parts by weight hydroxyethyl methacrylate. Also,55 parts of the phthalic-derived monomer of Example II was blended with45 parts hydroxyethyl methacrylate. Both of these blends were formulatedwith identical curing and stabilizing systems, providing anaerobicadhesive compositions C and D respectively. The adhesive compositionswere placed between the mating threads of cleaned 3/8 inch plain steelfasteners and allowed to cure at room temperature for 7 days. Torquemeasurements in inch-lbs. were then taken at room temperature and after2 hours at 120° C. with the following results:

    ______________________________________                                                             Prior Art                                                       Adhesive C    Adhesive D                                                      Breakaway                                                                             Prevailing                                                                              Breakaway Prevailing                                        Torque  Torque    Torque    Torque                                     ______________________________________                                        Room Temp.                                                                             316       360 +     300     360 +                                    120° C.                                                                          92       48         30     40                                       ______________________________________                                    

EXAMPLE IV

As a further example of monomer type I, one mol (86 g) methacrylic acidwas reacted with 1.05 mol (157.5 g) phenyl glycidyl ether in a fourneck, round bottom flask equipped with a condenser, agitator,thermometer and bubbler tube. Ten ml triethylamine was added as acatalyst and the contents heated and agitated with aeration at 60°-80°C. for 5 hours and 40 minutes. The contents of the flask were cooled and81.7 g (0.83 mol) maleic anhydride added. An additional 10 mltriethylamine was added, and the contents heated to 100° C. withagitation for 1 hour.

Fifty parts by weight of this monomer were blended with fifty partshydroxyethyl methacrylate and then formulated with a stabilizing andcuring system to provide an anaerobic adhesive composition. Thisadhesive was placed between the mating threads of cleaned 3/8 inch plainsteel fasteners and allowed to cure for 7 days at room temperature.Torque measurements in inch-lbs. were taken first at room temperature,then after 2 hours at 120° C., and then after 20 hours at 120° C. Thefollowing data were obtained:

    ______________________________________                                                   Breakaway Torque                                                                          Prevailing Torque                                      ______________________________________                                        Room Temp.   336           192                                                120° C. after 2 hrs.                                                                 53           32                                                 120° C. after 20 hrs.                                                               125           70                                                 ______________________________________                                    

EXAMPLE V

An acrylic monomer representative of monomers (IV) and (V) was preparedby reacting 48 grams (0.49 mols) maleic anhydride with 80 grams (0.62mols) hydroxyethyl methacrylate and 89.2 grams (0.51 mol equivalents) ofthe diglycidyl ether of bisphenol-A. The reactants were combined in aflask reactor as described in Example I, then heated and agitated withaeration to 67° C. Eight ml. of triethylamine catalyst was added, andthe reaction mixture maintained at 80°-90° C. for 101/2 hours until anacid value of 13 was obtained.

EXAMPLE VI

In order to demonstrate the improved hot strength imparted to ananaerobic adhesive system by the monomer of Example V, 50 parts byweight of the monomer of Example V was blended with 50 parts by weightof a well-known anaerobic adhesive monomer, hydroxyethyl methacrylate,and then formulated with a suitable curing and stabilizing system toprovide adhesive system E. This adhesive was compared with an anaerobicadhesive containing the identical curing and stabilizing system, buthaving only hydroxyethyl methacrylate as the polymerizable monomeringredient (adhesive F). The adhesive compositions were placed betweenthe mating threads of cleaned 3/8 inch plain steel fasteners and allowedto cure 24 hours at room temperature. Torque measurements in inch-lbs.were taken first at room temperature and then after holding at 120° C.for 16 hours. The following data were obtained:

    ______________________________________                                                             Prior Art                                                       Adhesive E    Adhesisve F                                                     Breakaway                                                                             Prevailing                                                                              Breakaway Prevailing                                        Torque  Torque    Torque    Torque                                     ______________________________________                                        Room Temp.                                                                             300       360 +     300     300 +                                    120° C.                                                                         164       160       140     64                                       ______________________________________                                    

These results establish that, while both novel monomer adhesive system Eand prior art system F exhibit good shear strength the novel monomer ofExample IV imparts a surprisingly increased hot strength to adhesivesystem E.

EXAMPLE VII

Another acrylic monomer representative of monomers (I) was prepared byreacting 108.1 grams of maleic anhydride with 157.7 grams ofhydroxyethyl methacrylate and 8 ml of triethylamine catalyst, which werethen agitated for about 2 hours, the catalyst having been added afteragitation began. The reaction was exothermic, and the monomer thatformed was allowed to cool to room temperature.

EXAMPLE VIII

The monomer of Example VII (38.2 grams) was reacted in the presence oftriethylamine with 110 grams (a 3% excess) of a high molecular weightliquid polyepoxide aliphatic glycidyl ether in order to prepare amonomer (IV) wherein R₄ is alkoxy of over 100 carbon atoms, the reactionhaving been assisted by agitation and heating in an oven at about 100°F. Fifteen grams thus formed was blended with 10 grams of hydroxyethylmethacrylate and into a suitable curing and stabilizing system in orderto prepare an anaerobic adhesive system G.

An adhesive system H was prepared to be substantially identical withadhesive system G, except the monomer according to this invention wasreplaced with a monomer prepared by reacting 8.6 grams of a prior artmonomer, methacrylic acid, with 69.5 grams (a 3% excess) of the samepolyepoxide used in preparing System G. The reaction was carried out inthe presence of 0.8 ml of triethylamine, and the reaction product wasblended into the same curing and stabilizing system of adhesive systemG.

Both adhesive compositions were placed between the mating threads ofcleaned 3/8 inch diameter plain steel fasteners (24 threads per inch)and allowed to cure at room temperature for 24 hours. Torquemeasurements in inch-lbs. were taken first at room temperature and thenafter holding at 120° C. for 20 hours. The following data were obtained:

    ______________________________________                                                             Prior Art                                                       Adhesive G    Adhesive H                                                      Breakaway                                                                             Prevailing                                                                              Breakaway Prevailing                                        Torque  Torque    Torque    Torque                                     ______________________________________                                        Room Temp.                                                                             123       113       100     130                                      120° C.                                                                          58       38         53      30                                      % Hot    --        33.6%     --        23%                                    Strength                                                                      Retained                                                                      ______________________________________                                    

These data show that adhesive system G exhibits enhanced shear strength(breakaway torque at room temperature) when compared with system H, thatthe adhesive system G exhibits about the same or a slightly increasedhot strength (prevailing torque at elevated temperatures) over the priorart adhesive, and that the percentage hot strength retention of adhesivesystem G was better than that of adhesive system H.

EXAMPLE IX

An acrylic monomer representative of monomers (I) was prepared having anR group wherein q is 3 and X is --O-- by reacting 174 grams (3 mols) ofpropylene oxide with 86 grams (1 mol) of methacrylic acid in thepresence of 13 grams of triethylamine catalyst, the reaction beingassisted by agitation, after which 62.8 grams of the monomer (withoutinternal unsaturation) thus prepared was reacted with 23.4 grams (about95% of theoretical) of maleic anhydride, with agitation and heating atabout 35° C. for 24 hours to prepare a monomer (I) having internalunsaturation according to this invention. Thereafter, 30 grams of thisinternally unsaturated monomer were blended with 20 grams ofhydroxyethyl methacrylate and blended into an adhesive system havingsuitable curing and stabilizing agents.

This adhesive system was applied to the mating threads of cleaned 3/8inch steel fasteners and allowed to cure for 24 hours at roomtemperature, after which torque measurements were made. The breakawaytorque was found to be 160 inch-lbs. and the prevailing torque was 216inch-lbs.

EXAMPLE X

A monomer was prepared as a guanidine salt by reacting 50 grams of themonomer of Example VII with 17.4 grams (about 95% of theroetical) ofguanidine carbonate, with agitation while heating at about 35° C. Themonomer guanidine salt thus prepared was blended in a 1:1 weight ratiowith hydroxyethyl methacrylate and then with suitable curing andstabilizing agents to form an adhesive system that was applied to thethreads of 3/8 inch steel fasteners and allowed to cure for 24 hours atroom temperature. The breakaway torque at room temperature was 324inch-lbs., and the prevailing torque at room temperature was 248inch-lbs.

EXAMPLE XI

An ester of monomer (I) was prepared by reacting 100 grams of themonomer prepared in Example VII with 28.2 grams (a 20% excess) ofpropylene oxide, the reaction being carried out with agitation, theproduct being an ester of monomer (I), 25 grams of which were blendedwith a suitable curing and stabilizing system to prepare an anaerobicadhesive. This adhesive was placed on the threads of clean 3/8 inchsteel fasteners and was allowed to cure for 4 days at room temperature.The breakaway torque was 136 inch-lbs., while the prevailing torque was135 inch-lbs.

EXAMPLE XII

Maleic anhydride (152.4 grams) was reacted with 222.4 grams ofhydroxyethyl methacrylate and 11.22 ml of triethylamine, followed byagitation for two days at room temperature. One part by weight of themonomer thus formed was combined with 1 part by weight of hydroxyethylmethacrylate, and 50 grams of the resultant monomer product was combinedwith 5.6 grams (about 95% of theoretical) of potassium hydroxide,followed by agitation overnight, after which the potassium salt of themonomer thus formed was blended into a suitable anaerobic adhesivesystem including curing and stabilizing agents, and this adhesiveformulation was tested in the same manner as specified in Example XI,except the cure time was 7 days, to provide a breakaway torque of 327inch-lbs. and a prevailing torque of 192 inch-lbs.

EXAMPLE XIII

Twenty-five grams of the resultant monomer product of Example XII werecombined with 1.35 grams (about 95% of theoretical) of calcium oxide,followed by stirring overnight and formulation into a suitable anaerobicadhesive system, which was tested in accordance with Example XII asproviding 324 inch-lbs. of breakaway torque and 366 inch-lbs. ofprevailing torque.

EXAMPLE XIV

Twenty-five grams of the resultant monomer product of Example XII werecombined with 6.7 ml (about 95% of theoretical) of triethylamine. Afteragitation overnight, the resulting amine salt was blended into asuitable anaerobic adhesive system and tested in accordance with ExampleXII to yield a breakaway torque of 288 inch-lbs. and a prevailing torqueof 177 inch-lbs.

EXAMPLE XV

A further 25 grams of the resultant monomer product of Example XII werecombined with 3.1 ml (about 95% of theoretical) of 29% ammonia in awater solution, followed by agitation and reaction overnight andblending into a suitable anaerobic adhesive system. Testing inaccordance with Example XII showed a breakaway torque of 98 inch-lbs.and a prevailing torque of 78 inch-lbs.

EXAMPLE XVI

Another 25 grams of the resultant monomer product of Example XII werecombined with 3.5 grams (about 95% of theoretical) of n-butylamine andallowed to react overnight with agitation, followed by formulation intoa suitable anaerobic adhesive system and testing in accordance withExample XII to yield 185 inch-lbs. of breakaway torque and a prevailingtorque of 129 inch-lbs.

EXAMPLE XVII

Twenty-five grams of the resultant monomer product of Example XII wascombined with 1.96 grams (about 95% of theoretical) of zinc oxide, thereaction being allowed to continue with agitation over the weekend. Theresultant zinc salt of the monomer was blended into a suitable anaerobicadhesive system including curing and stabilizing agents, which systemwas tested in accordance with Example XII to yield a breakaway torque of342 inch-lbs. and a prevailing torque of 369 inch-lbs.

EXAMPLE XVIII

One part by weight of the internally unsaturated monomer prepared inExample IX was blended with one part by weight of hydroxyethylmethacrylate and with suitable curing and stabilizing agents into ananaerobic Adhesive J. One part by weight of the monomer without internalunsaturation prepared in Example IX was blended with one part by weightof hydroxyethyl methacrylate and with suitable curing and stabilizingagents into an anaerobic Adhesive K.

Both adhesive systems were applied to the mating threads of cleaned 3/8inch steel fasteners and allowed to cure for 24 hours at roomtemperature, after which torque measurements were taken. Then furthertorque measurements were made after holding at 120° C. for 48 hours. Thefollowing results were observed, the torque measurements being ininch-lbs.

    ______________________________________                                               Adhesive J    Adhesive K                                                      Breakaway                                                                             Prevailing                                                                              Breakaway Prevailing                                        Torque  Torque    Torque    Torque                                     ______________________________________                                        Room Temp.                                                                             171       207       76      60                                       120° C.                                                                         105       134       13      21                                       % Strength                                                                             61.4%     64.7%     17.1%    35%                                     Retained                                                                      ______________________________________                                    

From these data, it is seen that the adhesive system according to thisinvention exhibited much greater retention of its adhesive strength whensubjected to increased temperature conditions than did the other systemtested.

Obviously, many modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof, and therefore, only such limitations should be imposed asare indicated in the appended claims.

I claim:
 1. An anaerobic adhesive composition, comprising: an acrylicmonomer having the general formula: ##STR14## wherein A is ##STR15##where R" is a member selected from the group consisting of hydrogen,chlorine, methyl and ethyl radicals, and where R₂ is an unsaturateddivalent alkyl or substituted alkyl group of from 2-4 carbon atoms or anunsaturated divalent carbocyclic aliphatic ring of from 4-9 carbonatoms, and where R is ##STR16## where p is an integer of from 0 to 2, qis an integer of from 1 to 3, R₁ is a member selected from the groupconsisting of hydrogen, methyl, ethyl, chloromethyl, methylol, phenyl,methoxyphenyl, methoxybutyl, methoxyallyl and ##STR17## radicals whereR" is as previously defined, and where X is a member selected from thegroup consisting of --O--, --NH-- and --NR'-- where R' is a benzylradical or an alkyl group of from 1-4 carbon atoms; wherein R₄ is amember selected from the group consisting of alkyl of 1-4 carbon atoms,alkoxy of 2-120 carbon atoms, alkylidene oxy-aryl, methylol alkoxy aryl,cyclohexadiene dioxide, cyclopentadiene dioxide, alkoxy hydantoin andalkoxy aryl sulfone; n is 0 or 1; and u is an integer of from 1 to 5;said acrylic monomer being in combination with a metal activatablepolymerization catalyst and a polymerization inhibitor.
 2. The adhesivecomposition of claim 1 wherein n is 1, u is 1 and R₄ is the alkylideneoxy aryl radical

    --CH.sub.2 O--Ph--C(R.sub.6).sub.2 --Ph--OCH.sub.2 --

where Ph is phenyl and R₆ is a member selected from the group consistingof hydrogen, methyl, ethyl, propyl and butyl radicals.
 3. The adhesivecomposition of claim 1, wherein X is oxygen.
 4. The adhesive compositionof claim 1, wherein said catalyst is an organic hydroperoxide catalyst,and said inhibitor is a quinone inhibitor, in further combination with apromoter selected from the group consisting of organic amines, imides,sulfimides, and mixtures thereof.
 5. The adhesive composition of claim 2wherein R" is methyl, R₂ is --HC═CH--, R is --CH₂ CH₂ O-- and R₆ ismethyl.
 6. The adhesive composition of claim 1, blended with one or morepolymerizable acrylic monomers.
 7. The adhesive composition of claim 1,blended with one or more polymerizable acrylic monomers selected fromthe group consisting of hydroxyethyl methacrylate, hydroxypropylmethacrylate, trimethylolpropane trimethacrylate, dibromopropylmethacrylate, diethylene glycol dimethacrylate, triethylene glycoldimethacrylate, dimethylaminoethyl methacrylate, tetraethylene glycoldimethacrylate, dipropylene glycol dimethacrylate, methyl methacrylate,ethyl methacrylate, propyl methacrylate, polyethylene glycoldimethacrylate, di-(pentamethylene glycol)dimethacrylate, n-butylmethacrylate, trimethylolpropane triacrylate, tetraethylene glycoldiacrylate, isobutyl methacrylate, tetraethylene glycoldi-(chloroacrylate), diglycerol diacrylate, diglyceroltetramethacrylate, butylene glycol dimethacrylate, ethylene glycoldimethacrylate, neopentyl glycol diacrylate, and tetrahydrofurfuralmethacrylate.
 8. The anaerobic adhesive composition according to claim1, wherein q is 1.